Multistage LDPC encoding

Abstract

Low-density parity-check (LDPC) encoding is performed by encoding input data using a first sub-matrix of a parity check matrix to obtain intermediate data. The parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion. The intermediate data is encoded using the matrix inversion of the second sub-matrix of the parity check matrix.

What is claimed is: 
     
       1. A system for performing low-density parity-check (LDPC) encoding, comprising:
 a first encoder configured to encode input data using a first sub-matrix of a parity check matrix to obtain intermediate data, wherein:
 the parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion; 
 the parity check matrix is an m×n matrix; 
 the first sub-matrix is an m×(n−m) matrix; and 
 the matrix inversion of the second sub-matrix is an m×m matrix; and 
 
 a second encoder configured to encode the intermediate data using the matrix inversion of the second sub-matrix of the parity check matrix. 
 
     
     
       2. The system of  claim 1 , wherein the parity check matrix includes a quasi-cyclic low-density parity-check (QC-LDPC) parity check matrix. 
     
     
       3. The system of  claim 1 , wherein the parity check matrix is a full rank matrix. 
     
     
       4. The system of  claim 1 , wherein:
 the second encoder is configured to encode the intermediate data by generating parity data; and 
 the system further includes a combiner configured to combine the parity data with the input data to obtain LDPC encoded data. 
 
     
     
       5. The system of  claim 1  further comprising storage configured to store the encoded intermediate data generated by the first encoder. 
     
     
       6. The system of  claim 1  further comprising a first buffer and a second buffer, wherein the first buffer is configured to store in the first buffer a first set of intermediate data received from the first encoder while simultaneously the second buffer is configured to pass a second set of intermediate data from the second buffer to the second encoder. 
     
     
       7. The system of  claim 1 , wherein the first encoder is configured to:
 divide up the input data into a plurality of portions; and 
 repeatedly use the first encoder to encode each of the plurality of portions. 
 
     
     
       8. A system for performing low-density parity-check (LDPC) encoding, comprising:
 a first encoder configured to encode input data using a first sub-matrix of a parity check matrix to obtain intermediate data, wherein the parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion; and 
 a second encoder configured to encode the intermediate data using the matrix inversion of the second sub-matrix of the parity check matrix, wherein the second encoder is configured to:
 divide up the intermediate data into a plurality of portions; and 
 repeatedly use the second encoder to encode each of the plurality of portions. 
 
 
     
     
       9. A method for performing low-density parity-check (LDPC) encoding, comprising:
 using a first encoder to encode input data using a first sub-matrix of a parity check matrix to obtain intermediate data, wherein the parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion; and 
 using a second encoder to encode the intermediate data using the matrix inversion of the second sub-matrix of the parity check matrix, including by:
 dividing up the intermediate data into a plurality of portions; and 
 repeatedly using the second encoder to encode each of the plurality of portions. 
 
 
     
     
       10. The method of  claim 9  further comprising storing data encoded using the method recited in  claim 9  in magnetic disk storage. 
     
     
       11. The method of  claim 9 , wherein the parity check matrix includes a quasi-cyclic low-density parity-check (QC-LDPC) parity check matrix. 
     
     
       12. The method of  claim 9 , wherein the parity check matrix is a full rank matrix. 
     
     
       13. The method of  claim 9 , wherein:
 using the second encoder includes generating parity data; and 
 the method further includes combining the parity data with the input data to obtain LDPC encoded data. 
 
     
     
       14. The method of  claim 9  further comprising storing the encoded intermediate data generated by the first encoder. 
     
     
       15. The method of  claim 9  further comprising using a first buffer to store a first set of intermediate data received from the first encoder and using a second buffer to simultaneously pass a second set of intermediate data from the second buffer to the second encoder. 
     
     
       16. The method of  claim 9 , wherein using the first encoder includes:
 dividing up the input data into a plurality of portions; and 
 repeatedly using the first encoder to encode each of the plurality of portions. 
 
     
     
       17. A method for performing low-density parity-check (LDPC) encoding, comprising:
 using a first encoder to encode input data using a first sub-matrix of a parity check matrix to obtain intermediate data, wherein:
 the parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion; 
 the parity check matrix is an m×n matrix; 
 the first sub-matrix is an m×(n−m) matrix; and 
 the matrix inversion of the second sub-matrix is an m×m matrix; and 
 
 using a second encoder to encode the intermediate data using the matrix inversion of the second sub-matrix of the parity check matrix. 
 
     
     
       18. A computer program product for performing low-density parity-check (LDPC) encoding, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:
 encoding input data using a first sub-matrix of a parity check matrix to obtain intermediate data, wherein:
 the parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion; 
 the parity check matrix is an m×n matrix; 
 the first sub-matrix is an m×(n−m) matrix; and 
 the matrix inversion of the second sub-matrix is an m×m matrix; and 
 
 encoding the intermediate data using the matrix inversion of the second sub-matrix of the parity check matrix. 
 
     
     
       19. A computer program product for performing low-density parity-check (LDPC) encoding, the computer program product being embodied in a non-transitory computer readable storage medium and comprising computer instructions for:
 encoding input data using a first sub-matrix of a parity check matrix to obtain intermediate data, wherein the parity check matrix includes the first sub-matrix and a second sub-matrix having a matrix inversion; and 
 encoding the intermediate data using the matrix inversion of the second sub-matrix of the parity check matrix, including by:
 dividing up the intermediate data into a plurality of portions; and 
 repeatedly using the second encoder to encode each of the plurality of portions.